240hoke Posted July 24, 2005 Share Posted July 24, 2005 Not trying to be a techincal pain in the *** but... according to the SCCA rule book a vehicle weighing between 2001-3500 pounds must use 1.750 x .120 if mild steel is used. They recommend the use of mild steel because "chromium alloys present difficulties in welding and must be normalized to relieve stress" To keep the wall thickness at least .120 throughout the rollbar it is nessecary to use .134 due to variences in wall thickness from manufacturing and from streching that occurs when the metal is bent. Im not trying to stick up for S&W really but if you wanna pass tech and your a company that sells stuff to pass regualtions there are certain things that must be used. And I also think in many cases SCCA rules are good guidlines to building a safe street car. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 24, 2005 Share Posted July 24, 2005 Not trying to be a techincal pain in the *** but... according to the SCCA rule book a vehicle weighing between 2001-3500 pounds must use 1.750 x .120 if mild steel is used. They recommend the use of mild steel because "chromium alloys present difficulties in welding and must be normalized to relieve stress" To keep the wall thickness at least .120 throughout the rollbar it is nessecary to use .134 due to variences in wall thickness from manufacturing and from streching that occurs when the metal is bent. Im not trying to stick up for S&W really but if you wanna pass tech and your a company that sells stuff to pass regualtions there are certain things that must be used. And I also think in many cases SCCA rules are good guidlines to building a safe street car. This is wrong, right John and Katman? I thought 1.5 x .120 wall was the requirement. I suppose it might depend on what class you're in. What class did you look for Austin? This is important to me because I have arranged to get a hoop bent in 2 weeks, and we're going to do 1.5 x .120. Also I asked him about the wall thickness thing, and he said that sometimes tube comes up .118 when it's listed as .120. His supplier for materials errs on the thick side just for this reason, so his stuff is commonly between .120 and .122. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 24, 2005 Share Posted July 24, 2005 I just looked at my SCCA GCR (2004) section 18.1. It states: Minimum tubing sizes for (all shoroom stock, Touring and Improved Touring Category automobiles registered after June 1, 1994) for all required cage elements (All dimensions in inches): Up to 1500 lbs--------------------1.375 x 0.095 DOM/Seamless/Alloy 1501 to 2200 lbs-----------------1.500 x 0.095 DOM/Seamless/Alloy 2201 to 3000 lbs-----------------1.500 x 0.120 DOM/Seamless/Alloy ------------------------------------1.625 x 0.120 DOM/Seamless/Alloy ------------------------------------1.750 x 0.095 DOM/Seamless/Alloy It also states that ERW is not allowed in any car registered with SCCA after01/01/2003. Weights are without driver and fuel. Quote Link to comment Share on other sites More sharing options...
240hoke Posted July 25, 2005 Share Posted July 25, 2005 Well i got my information out of the "appendix j, rollbar specification, solo 1" section of my 20004 SCCA national solo book. Its on page 276, im was just typing whats written... im not really into scca racing right now so maybe im wrong I think the difference is that i am looking in a solo book and this is the specification for rollbars and not cages but i dunno. Im here to learn correct me. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 25, 2005 Share Posted July 25, 2005 I looked at the page that you referred to and sure enough it states the following for cars 2001-3500 lb: 1.750 x 0.120--------------mild steel 1501-2500 lb-------------1.625 x .095------Alloy Steel BTW, I have looked at the pictures of your cage. NICE WORK! Some of us are just anal about weight. My main hoop and other "required" tubes are 1.625 x 0.120 (4130). All of the optional tubing is either 1.625 x 0.083 or 1.625 x 0.065. If I had it to do again, I would have used 0.095 rather than 0.120 for my main hoop. One of my favorite things about this site is the way each of us arrive at different solutions to the same problem. I look forward to watching the progress on your car. Jon had a concern about using 1.5 x 0.120 and wall thickness. Section 18.1 allows for 0.010" below nominal thickness. So as long as you stay above .110 you're golden. Dan Quote Link to comment Share on other sites More sharing options...
Mikelly Posted July 27, 2005 Share Posted July 27, 2005 My cage was designed and built by a NASA and SCCA tech inspector and we used 1.5X.120 mild DOM. For comparison, the tubing came out to be about 1.25 pounds per foot of tubing... We used 68Ft. of tubing... So imagine how heavy the S&W cage is... Oh, and I got a 12 point S&W cage GIVEN to me with my Z when I bought it from Chris Cloud. I promtly sold it because of the design and weight. As noted elsewhere, you have to be careful on what "type" of SCCA event you envision running in. My cage would require the removal of the welds on the windshield Gussets to be considered ITS legal, and then I'd have to get a waiver for at least one other tie in point. On the other hand, You want to build it with as broad a spec coverage as possible, which was why I employed a shop like Pipe Motorsports to do my cage. That said, If I was going to install one, I'd do EXACTLY what 240Hoke did! Nice work! Mike Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 27, 2005 Share Posted July 27, 2005 Well I decided to go with 1.75 x .120 just to be on the safe side. I'd rather not have to redo this thing later on. Quote Link to comment Share on other sites More sharing options...
katman Posted July 27, 2005 Share Posted July 27, 2005 Just a reference point- using 1-3/4 .095 wall for an ITS cage, about 60 feet worth of tubing weighs 106 lbs. Using 1-1/2 .120 wall weighs about 126 lbs. The 1-3/4 .095 is lighter but also about 36% stiffer in bending (critical for door bars). Downside is it's bigger around so it encroaches on your cockpit more. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted July 28, 2005 Share Posted July 28, 2005 YUp, and that was the ONLY reason I went with the 1.5 inch tubing... That little bit of extra space around places like the steering wheel and rocker boxes was more of an issue with 1.75 tubing. To each his own, But I'm very pleased with my track day cage. Mike Quote Link to comment Share on other sites More sharing options...
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